The background art of the technical field of the present invention is described in Japanese Patent Laid-Open No. 2013-195326 (Patent Literature 1). Patent Literature 1 recites “the object detection device includes regions for detecting the spatial position of a hand, and comprises: a first light-emitting section 1A, a second light-emitting section 1A2, and a light-receiving section 1B that are arranged such that, when, in one of the regions which correspond to the hand, the distance with respect to the hand is equal to or less than a threshold distance, it is detected that the hand is in the region; and a sensor driver 10 configured such that, when detecting the hand is in the region A and the region B, sets the threshold distance for the region C to a threshold distance corresponding to predetermined wipe operation of the hand”.